dm thin: fix stacking of geometry limits
Do not blindly override the queue limits (specifically io_min and
io_opt). Allow traditional stacking of these limits if io_opt is a
factor of the thin-pool's data block size.
Without this patch mkfs.xfs does not recognize the thin device's
provided limits as a useful geometry (e.g. raid) so these hints are
ignored. This was due to setting io_min to a useless value.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 88f2f80..21328a3 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2648,9 +2648,17 @@
{
struct pool_c *pt = ti->private;
struct pool *pool = pt->pool;
+ uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
- blk_limits_io_min(limits, 0);
- blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
+ /*
+ * If the system-determined stacked limits are compatible with the
+ * pool's blocksize (io_opt is a factor) do not override them.
+ */
+ if (io_opt_sectors < pool->sectors_per_block ||
+ do_div(io_opt_sectors, pool->sectors_per_block)) {
+ blk_limits_io_min(limits, 0);
+ blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
+ }
/*
* pt->adjusted_pf is a staging area for the actual features to use.
